1. Field of the Invention
The present invention relates generally to firearms and, more particularly, to a method and apparatus compensating for muzzle lift due to recoil.
2. Description of the Prior Art
It is well known in the art of firearms that when the propellant accelerates a projectile through the bore, a reactive force or “recoil,” is exerted on the firearm in a direction parallel to the bore axis and opposite to the accelerating direction of the projectile. The recoil force is transferred to the person holding the firearm and, because the general construction of firearms locates the bore axis above the weapon's center of mass, and above the location that user grips the firearm, it exerts a torque moment relative to that center of mass and grip point. This recoil-induced torque causes the muzzle of the firearm to lift. Such muzzle lift, generally speaking, is more pronounced with pistols than rifles and shotguns; a pistol is typically less massive than a rifle, the vertical distance from the grip surface to the bore axis of pistol is greater than the comparable distance for a rifle and, further, a person often holds a pistol with his or her arm extended. Muzzle lift is also a problem with automatic rifles, because their rapid rate of firing exerts many successive torque impulses, making the muzzle tend to “climb.”
Methods and devices are known that aim or purport to compensate for this muzzle lift. One such method is to form vents proximal to the muzzle of the firearm. Such vents extend in a generally upward direction, radial from the bore axis, exiting at an outer surface of the barrel. When the firearm is operated, the projectile travels through the bore and, after the projectile moves past the vent opening at the bore interior, a portion of the propellant gas passes through the vent and exits from the barrel in a generally upward direction, perpendicular to the bore. The exiting propellant exerts a force on the barrel, in opposite the direction that the vent extends outward from the bore center, i.e., generally downward. This force compensates, to some extent, the recoil force and resulting muzzle lift.
Muzzle vents, however, have numerous shortcomings. One is that the propellant gas exiting the vent presents a bright flash, typically directly in the user's line of sight to the target. The flash distracts the user and a causes a momentary blurring of the target image. Another shortcoming is that muzzle vents, particularly for pistols, are generally not adjustable. Therefore, the compensation force is fixed, without means for adjusting for the different physical strength and preference of different users, and without means for adjusting for different types of propellant and different projectile masses, typically referenced as “loads,” that can be used with the same firearm. Still another shortcoming of muzzle vents is that the downward force resulting from propellant exiting the muzzle vents is sufficient only to partially counteract the recoil-induced torque moment. Therefore, muzzle lift is not fully compensated.